For every 100,000 residents in Hawaii, there are 20 people over the age of 100 years of age compared to on the mainland where there is only 10 people over the age of 100 per 100,000 people according to a USC Doctor that did a study on Centenarians in Hawaii.

Here is a video about the study done by Dr. Murali D. Nair, Clinical Professor at the University of Southern California that attempts to explain this phenomena